Abstract: A process for the recovery of metal values, principally zinc and copper, from an aqueous acidic purge stream in a hydrometallurgical process by contacting the stream containing the iron, copper and zinc sulfates, along with trace amounts of other metallic sulfates with calcium oxide to bring the pH in the range 3.0-4.0, thence with sufficient ammonia to form the soluble tetrammine sulfates of copper and zinc, then separating the copper from the zinc, e.g. by hydroxy oxime-solvent extraction and thereafter recovering the zinc as zinc oxide by converting the zinc tetrammine sulfate to the hydroxide and removing ammonia from the complex.

Abstract: Sulfur monochloride is reacted with an ore containing iron, sulfur and a metal which forms a water soluble ammine complex or an ammonium-containing double salt, to yield metal chlorides and sulfur. The metal sought is solubilized with an aqueous solution containing ammonium ions to produce an aqueous solution of metal ammine complex or double salt and thereby separate such complex or salt from the iron and sulfur. The solution containing the sought metal values can then be subjected to electrowinning to recover the metal, or the metal can be precipitated as the metal oxide by the addition of sodium hydroxide. Sulfur and chlorine are recovered during the process and used to regenerate sulfur monochloride.

Abstract: An improved process for preparing highly concentrated salt solutions of metals of high purity from waste metal sludges at superior dissolution rates is achieved by preparing, concentrating and washing the sludge containing insoluble metal hydroxide under specific conditions to safeguard against the solids being exposed to air or dried out. The wet sludge is then dissolved in a dilute acid. The resultant solution can be used directly e.g. as make up in many electrolytic metal finishing processes to compensate for drag out losses occurred, or as the primary metal source in electrolytic processes employing insoluble anodes. Other specific uses for the process include the preparation of aluminum sulfate coagulants.